[brianshaw]

Two things to have checked out: the oven's thermostat and the calibration of your ovens temp knob. If the thermostat is going on the fritz you could see irregular heating like you described. If the knob isn't calibrated you'll not know what the temp is when you're baking unless you have a separate thermometer (which you should have anyway). Oops, you have one. Have the ovens thermostat checked!!!!

 

[brianshaw]

By the way, I feel your pain. My mom had the same problem, plus an igniter that was going to fail soon. So I replaced those parts and all was well. Two weeks later I visited and she had a new oven. She was so upset by the problems that even when fixed she was upset at the oven and wanted it out of her house!

 

[brianshaw]

Both are relatively easy for somebody skilled at DIY. The amount of disassembly of the oven is often the most challenging aspect. For older equipment, having to deal with generic aftermarket parts can sometimes make it challenging also. But DIY is a whole lot more affordable than hiring a pro. Seems like both stove/oven and refrigerator repairs are priced so high that replacement becomes a more sensible alternative. It's sad but true.